The use of stents to hold open the lumens of blood vessels has become quite widespread. The Palmaz-Schatz stent marketed by Johnson & Johnson Interventional Systems of Warren N.J. has become universally recognized as the premier device for holding open occluded blood vessels, including the occluded coronary arteries. Nonetheless, the use of these stents is limited to a certain degree. That is, it is not always possible to prevent thrombosis arising near the lesion site, and there is always the possibility of occlusion of the lumen in the days following stent implantation. It would be desirable to provide the patient with protection against such undesirable events. This therapy, it is believed, helps to prevent early thrombus. Also, it appears that the heparin treatment will help to reduce the occurrence and the degree of restenosis.
With this in mind, there is a need for technology which will enable the interventionalist to apply heparin or other therapy to the surface of an implanted device in optimum degrees, But, the theory about such treatment has heretofore been an all or nothing approach. Simply, the interventionist believed that the amount of heparin applied and the nature of its attachment would not matter. There could be no middle ground. As this mindset set in, there simply would be no attention paid to researching the way to apply varying amounts of heparin, and, for that matter, whether the varying amounts of heparin on the stent actually could matter.